- Eunice Oh
have been many natural disasters and impacts due to a rise in earth’s temperature, the global warming. According to NASA’s Goddard Institute for Space studies, 1.4 degrees Fahrenheit have increased around the world since 1880. In addition, the increasing did not stop, an d it is increasing at a faster rate in the last two decades (SITE1). This warming phenomenon fluctuates the ecosystem an d may lead to extinction in extreme cases. Therefore, an experiment on observ ing effects of rise in temperature on pollen germination can be used a deduction for a bigger picture. The goal of this experiment was to observe the effect of temperature on the pollen germination of Delosperma cooperi (trailing iceplant) and Tulbaghia violacea (society garlic) . Pollen is a fine powder that contains microgametophytes of seed plants and it produces the male game tes. When pollination occurs, the pollen germinates and a pollen tube is produced (SITE2). The p ollen germination refers to the growth of a pollen tube from pollen grains. In nature, the germination happens when the stigma is hydrated and water is available. It can also be achieved in vitro using germination media and hanging drop method (SITE 3). T he data w as analyzed statisti cally to confirm if the data is statistically significant by u tilizing Q10 values and Dixon Q test. I hypothesized that the increase in temperature would result in higher pollen germination percentage and longer pollen tubes than the room temperature control .
Materials and Methods:
The solutions used for this experiment include the basic germination media (1mM KCl, 0.1mM CaCl2, 1.6mM H3BO3, 10% glucose )and distilled water. Unique equipment used were compound microscope, gasket, depression slide, slides warmer, petri dish, kim wipes, and pipette tips. The b asic germination media was used to initiate the pollen germination and the hanging drop method was utilized for the observation. A gasket was placed on top of the slide in order to create an area for the hanging drop to be intact with the cover slide . The slides were placed in the humanity chamber to prevent the drying. Two sets of the hanging drops were prepared, which were for the higher temperature (37 degrees celcius), room temperature (27 degrees celcius). The negative control was prepared by observing the pollen alone without any germination media.
Statistical analysis method:
Dixon Q test
: Q= (gap)/
P-v alue: R is the rate and T is the t emperature in Celsius degrees or kelvins .
The elongation rates of Delosperma cooperi room temperature control were about 3 times slower compared to the high temperature control ( 0.278 um/min vs. 0.686 um/min ).
The percent germination was
significantly different for the two controls, which the room temperature control had ~ 20% and the higher temperature control had ~60% germination after 120minutes from theinitiation. Dixon Q-test result indicated the data point 0.78 4 um/min of the higher temperature control as an outlier since the P value was below the threshold point, 0.05.
The mean elongation rate for the room temperature was 0.31
37 um/min and 0.45 38 um/min for the higher temperature control. The P value was calculated to be 0.0447, which indicate d that the result is statistically significant at a 95% confidence interval since P is less than 0.05.
Q10 temperature coefficient
was calculated by using the equation (R2/R1) 10/(T2-T1) , where R is rate and T is temperature used from the experiment. The calculation was (0.674/0.188)^(10/37-27) and the Q 10 Value forDelospermacooperiâ€‹â€‹ is 3.59 .
Discussion: The goal of this experiment was to observe the effect of the change in temperature on pollen germination, especially focusing on aspects of improving percentage germination and the pollen tube elongation.
The result shows that the higher temperature yielded in an improvement in both percentage germination and pollen tube length growth .
The percent germination was about three times faster when compared to the positive control. The also much faster in the higher temperature control, with the highest rate observed 0.784 microns/ The statistical analysis supports this data, since the P-value at the 95% confidence interval is lower than 0.05 and Q10 value is higher than 2. Q10 is a unit-less measurement that allows t o verify if th e change of a biological or chemical system is temperature dependent. ( SITE 4) In addition, higher percentage germination was observed from the higher temperature control . These result correspond to the published article , in which Delosperma cooperi is more adapted to a higher temperature environment (SITE 5).
was opposite from what was observed in Delosperma cooperi. The pollen germination percentage and pollen tube growth were more effective in the room temperature control. Tulbaghia violacea is known to be better suited in the colder environment , and therefore the data corresponds to this fact (SITE 6). However, the data was determined to be not significantly significan t. The source of error includes a part of basic germination media merging with the gasket. While observing and putting the observation slide back to the humidity chamber, the media moved and touched the gasket, which the result may not be as accurate as we wanted. In addition, due to the gasket, the pollens could not be observed under the 40x magnification. Although pollen tubes could be observed under the 10x magnification, the 40x could have yielded in more accurate pollen tube measurements. For the flower, even though the pollen seemed to be mature and powdery, some of the pollens seemed to be dead or too mature when observed under the microscope.
A possible future experiment includes testing
various flower pollens in both lower and higher temperature. In addition, it would be good if the gasket is not used, and therefore the observation can be done under the 40x magnification.
Leistner, O. A. (ed.). 2000.Seed plants of southern Africa: families and genera.Strelitzia10. National Botanical Institute, Pretoria.
MozaffarEbrahim& Edmund John Pool (2010). “The effect ofTulbaghiaviolaceaextracts on testosterone secretion by testicular cell cultures”.Journal ofEthnopharmacology132(1): 359–361
Reyes, A.B.,Pendergast, J.S., andYamazaki, S. 2008. Mammalian peripheral circadian oscillators are temperature compensated. J.Biol. Rhythms 23: 95-98.
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2. Raven, Peter H.; Ray F. Evert, Susan E. Eichhorn (2005).Biology of Plants, 7th Edition. New York: W.H. Freeman and Company Publishers. pp.504–508.
3. Pfahler PL (1981).“In vitro germination characteristics of maize pollen to detect biological activity of environmental pollutants”.Environ. Health Perspect.37: 125–32.
4. Reyes, A.B.,Pendergast, J.S., andYamazaki, S. 2008. Mammalian peripheral circadian oscillators are temperature compensated. J.Biol. Rhythms 23: 95-98.